Analyses of methylation status of CpG islands in promoters of miR-9 genes family in human gastric adenocarcinoma

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In the recent years deregulation for microRNAs expression pattern have emerged as a possible molecular factor for carcinogenesis. It has been reported that the expression of miR-9 was down-regulated in human gastric adenocarcinoma. To figure out the molecular mechanism of this down regulation, the methylation status in promoters of miR-9 family loci were compared in the human gastric adenocarcinoma samples with their normal margins. Using a methylation specific PCR technique the methylation status of miR-9 family loci were compared between 30 pairs of primary human gastric adenocarcinoma samples with their normal margins. The methylation of miR 9-1 status showed no specific difference in promoter methylation pattern in tumor and normal specimens, while in the miR-9-2 locus were unmethylated in both types of tissues. The promoter of miR-9-3 locus seems to be specifically methylated in tumor and their normal margin tissues. Our data revealed methylation of these CpG islands were not meaningfully different between normal and tumor gastric adenocarcinoma specimens and the methylation status of promoter may not be able to account for alteration of miR-9 expression in this type of gastric cancer.